In the context of in-vitro neural interfaces for neurostimulation via extracellular calcium modulation, we in-vestigated by finite element numerical simulations the electrical cross-talk between a polymeric ionic actuator for calcium release and a microelectrode for neural recording. Several device designs have been explored to mitigate the cross-talk. A separation wall between the ionic emitter and the sensing electrode has been found to remarkably improve the ratio between the sensed action potentials and the disturb induced by ionic actuation.